Are meetings mandatory?
No. None of the meetings are "mandatory". Once a candidate has been raised to the 3rd degree, participation is completely voluntary and at the individuals will and pleasure. Further, a Mason is not obligated to go only to his lodge once all 3 degrees have been obtained and a certain degree of proficiency has been achieved. Once full membership is achieved, the Mason can go to any lodge or Masonic function.
There are certain protocols when visiting distant lodges.
Ideally, once you go through the degrees it is hoped that the new member will desire to attend the regular meetings and contribute to the organization as their time permits.